[refactor] group

1 files changed, 9 insertions, 6 deletions

diff --git a/hyperquirks.lisp b/hyperquirks.lisp
index dd65b4f..b765e69 100644
--- a/hyperquirks.lisp
+++ b/hyperquirks.lisp
@@ -208,12 +208,15 @@ E.g.
   "Group a list XS into consequtive sublists of size N, using the
 DEFAULT to fill in any remainder in the case the length of XS is not
 neatly divisible by N."
-  (loop for l on xs by (lambda (l) (nthcdr n l))
-        when (<= n (length l))
-          collect (subseq l 0 n)
-        else
-          collect (append l (loop repeat (- n (length l)) collect default))))
-
+  (loop
+    with len = (length xs)
+    for start from 0 to len by n
+    for end = (+ start n)
+    when (<= end len)
+      collect (subseq xs start end)
+    when (and (< start len) (> end len))
+      collect (nconc (subseq xs start)
+                     (loop repeat (- end len) collect default))))
 
 ;;; STRING FUNCTIONS